高手帮忙啊！！如何在HttpWebRequest请求时让Session不丢失

//1.aspx 

protected void Page_Load(object sender, EventArgs e)

    {

        //给会话添加一项

        Session.Add("ss", "ttttt");

        //请求2.aspx得到HTML

        string s = HttpWebResponsePost("http://localhost:1155/Web/2.aspx", "", "utf-8");        

        Response.Write(s);

    }



public static string HttpWebResponsePost(string url, string postData, string encodeType)

    {



        Stream outstream = null;

        Stream instream = null;

        StreamReader sr = null;

        HttpWebResponse response = null;

        HttpWebRequest request = null;

        Encoding encoding = Encoding.GetEncoding(encodeType);

        byte[] data = encoding.GetBytes(postData);



        try

        {

            request = WebRequest.Create(url) as HttpWebRequest;

            CookieContainer cookieContainer = new CookieContainer();

            request.CookieContainer = cookieContainer;

            request.AllowAutoRedirect = true;

            request.Method = "POST";

            request.ContentType = "application/x-www-form-urlencoded";

            request.ContentLength = data.Length;

            outstream = request.GetRequestStream();

            outstream.Write(data, 0, data.Length);

            outstream.Close();

            response = request.GetResponse() as HttpWebResponse;

            instream = response.GetResponseStream();

            sr = new StreamReader(instream, encoding);

            string content = sr.ReadToEnd();

            return content;

        }

        catch (Exception ex)

        {

           return string.Empty;

        }

    } 







//被请求的2.aspx

protected void Page_Load(object sender, EventArgs e)

    {

        Response.Write("request page... Session Count:"+Session.Count);

    }